A crop harvesting machine generally includes a crop header for cutting a standing crop including a header frame, a cutter sickle extending across a front cutter bar of the header frame for cutting the crop, and a transport system operable to transport the crop to a central discharge opening of the header so as to form a swath.
The machine further includes a tractor or other vehicle for carrying the header including a tractor frame having a first end and a second end, ground wheels for supporting the tractor in movement across the ground including a pair of transversely spaced first wheels at the first end, a mounting assembly at the first end of the tractor frame for supporting the header, and a lift linkage for raising and lowering the mounting assembly.
The crop header generally includes a header frame, an elongate cutter bar along a front edge of the frame including a cutter bar beam which carries a plurality of knife guards for guiding reciprocating movement of a sickle knife across a front edge of the cutter bar. When the crop header is of the draper header type, then on the header is also mounted rearwardly of the cutter bar a draper assembly including a first and second draper guide roller each arranged at a respective end of the draper assembly spaced apart along the cutter bar with an axis of each roller extending substantially at right angles to the cutter bar, a draper forming a continuous loop of flexible material wrapped around the rollers so as to define a front edge of the draper adjacent the cutter bar, a rear edge of the draper spaced rearwardly of the cutter bar, an upper run of the draper on top of the roller and a lower run of the draper below the rollers. The cut crop thus falls rearwardly onto the upper run of the draper and is transported longitudinally of the header.
The draper header type can be used simply for forming a swath in which case the material is carried to a discharge opening of the header and deposited therefrom onto the ground. Headers of this type can also be used for feeding a combine harvester so that the materials are carried to an adapter member positioned at the discharge opening of the header for carrying the materials from the discharge opening into the feeder housing of the combine harvester. Yet further, headers of this type can be used for hay conditioners in which the material from the discharge opening is carried into crushing rolls. It will be appreciated, therefore, that the use of the header is not limited to particular types of agricultural machine but can be used with any such machine in which it is necessary to cut a standing crop and to transport that crop when cut longitudinally of the header for operation thereon.
These crop headers may employ a height control system so as to regulate a height of the cutter bar above the ground, which allows for as much if not all of the standing crop to be harvested particularly when the crop is growing on uneven terrain.
Conventional height control systems use a sensor finger which is positioned so as to extend downwardly from the header frame to the ground to determine the above ground height of the cutter bar by physical contact of the finger therewith. In view of the ground contact of the sensor fingers suited for following the ground in a forward cutting direction, the sensor fingers are readily susceptible to damage under a variety of instances when the harvester is displaced across the ground in directions other than the conventional forward cutting direction. Furthermore, these systems typically include at least one spring arranged to bias the finger against the ground so that the finger follows same, however, adjusting the downward pressure of the sensor finger when deployed involves a complex mechanical process of manually adjust the spring position.
United States Patent Application Publication No. 2017/0064904 by CNH Industrial America LLC discloses one example of a harvester having a height control feature. The method includes positioning the header to a predetermined cut height set point, measuring a ground speed of the agricultural harvester, measuring a height of the header relative to a ground surface at a plurality of positions along a length of the header. The method further includes lowering the header towards a first adjusted cut height threshold if a measured height of one of the plurality of positions is above the predetermined cut height set point and the measured ground speed is less than a first predetermined ground speed. The subject application allows the automatic header height control software on an agricultural harvester to automatically deviate from the predetermined cut height set point. The height control is limited to correcting for ground forming a crown or a swale in the direction of travel, but does not accommodate for laterally sloped terrain.